Question

Match List-I with the List-II

List-I (Precipitating reagent and conditions)	List-II (Cation)
(A) \(NH_4Cl + NH_4OH\)	(I) Mn2+
(B) \(NH_4OH + Na_2CO_3\)	(II) Pb2+
(C) \(NH_4OH + NH_4Cl + H_2S gas\)	(III) Al3+
(D) dilute HCl	(IV) Sr2+

Choose the correct answer from the options given below:

• A. A-IV, B-III, C-II, D-I
• B. A-IV, B-III, C-I, D-II
• C. A-III, B-IV, C-I, D-II
• D. A-III, B-IV, C-II, D-I

Answer 1

The Correct Option is C

To solve the given problem, we need to match the reagents and conditions from List-I with the corresponding cations from List-II. Each reagent precipitates specific cations under given conditions:

1. (A) \(NH_4Cl + NH_4OH\):
   • This combination is commonly used to precipitate aluminum hydroxide, \(Al(OH)_3\), from solutions containing \(Al^{3+}\) ions.
2. (B) \(NH_4OH + Na_2CO_3\):
   • This combination is effective in precipitating carbonates of alkaline earth metals like strontium carbonate, \(SrCO_3\), thus it is associated with \(Sr^{2+}\).
3. (C) \(NH_4OH + NH_4Cl + H_2S\) gas:
   • In an alkaline medium provided by \(NH_4OH\) and \((NH_4)_2S\), sulfides of certain cations such as \(MnS\) can be precipitated. Here, it matches with \(Mn^{2+}\).
4. (D) Dilute HCl:
   • This is often used to precipitate chlorides of certain metal ions such as \(PbCl_2\). Therefore, it matches with \(Pb^{2+}\).

Based on the information above, the correct matching is:

• (A) \(NH_4Cl + NH_4OH\) matches \(Al^{3+}\) so it is III.
• (B) \(NH_4OH + Na_2CO_3\) matches \(Sr^{2+}\) so it is IV.
• (C) \(NH_4OH + NH_4Cl + H_2S\) gas matches \(Mn^{2+}\) so it is I.
• (D) Dilute HCl matches \(Pb^{2+}\) so it is II.

The correct option is A-III, B-IV, C-I, D-II.

Answer 2

The matching is based on the chemical properties and specific precipitation conditions for cations:
[A.] NH$_4$Cl + NH$_4$OH precipitates Al(OH)$_3$, hence matches with III. Al$^{3+}$.
[B.] NH$_4$OH + Na$_2$CO$_3$ precipitates SrCO$_3$, hence matches with IV. Sr$^{2+}$.
[C.] NH$_4$OH + NH$_4$Cl + H$_2$S gas precipitates PbS, hence matches with II. Pb$^{2+}$.
[D.] Dilute HCl precipitates MnCl$_2$, hence matches with I. Mn$^{2+}$.
Thus, the correct order is:
\[A -- III, B -- IV, C -- II, D -- I.\]